fix: run mocha with --exit flag

For some reason the tests hang when running on node 16+. Using the `--exit`
flag forces mocha to quit after the test run. This is definitely a bandaid but
all attempts to find the root cause have so far been unsuccessful. :/

package.json

@@ -6,7 +6,7 @@
     "lint": "eslint src test --ext js",
     "stylelint": "stylelint src/**/*.css src/components/**/*.css",
     "pretest": "npm run lint",
-    "test": "cross-env NODE_ENV=test nyc mocha \"test/spec/**/*.test.js\"",
+    "test": "cross-env NODE_ENV=test nyc mocha \"test/spec/**/*.test.js\" --exit",
     "tdd": "cross-env NODE_ENV=test nyc mocha --watch \"test/spec/**/*.test.js\"",
     "test:single": "cross-env NODE_ENV=test nyc mocha ",
     "test:functional": "cross-env NODE_ENV=test node ./test-functional/index.js",